1. Field of the Invention
This invention relates to a traffic control marker; more particularly, to a highly visible and permanent traffic control marker adapted for use with asphaltic pavements.
2. Description of the Prior Art
The most widely used traffic control marker is the painted line. Among the reasons for the continued, almost exclusive use of the painted line as a traffic marker are: relative economy, ease of application, lack of physical interference with pedestrian or vehicular traffic when applied to the pavement surface, and failure of many suggested substitutes to live up to their claimed advantages over the painted line. The use of painted lines, however, involves serious disadvantages, many of which were recognized in the prior art as early as 1925. U.S. Pat. Nos. 1,606,825, 1,728,275 and 1,966,318, for example, note that painted lines involve considerable expense and are but a temporary expedient on heavily traveled streets. While painted lines are more economical than other proposed traffic control markers, nevertheless frequent repainting, as is often required where traffic is heavy, does involve considerable expense and promises to become more expensive because of the rising cost of paint, labor and application machinery.
The very nature of the painting process aggravates these disadvantages. For example, heavily traveled areas must be painted at off-peak hours thereby generating expensive overtime labor costs. In addition, opening the newly painted pavement in response to traffic pressures in heavily traveled areas before the paint is fully set hastens the wearing process from the beginning.
Another disadvantage manifests itself when the painted line is viewed from a safety standpoint. By nature, the visibility of a painted line is greatest when first applied and decreases steadily until repainting is required. As a result, traffic is always exposed to an inadequate marker for a portion of the painting-repainting time cycle.
Prior art devices for overcoming the disadvantages of the painted line have been directed primarily to achieving near permanency of the marker. That is, the prior art sought permanency sufficient to provide that any increased cost of the marker over that of the painted line would be more than offset by saving the cost of repaintings over the life of the highway surface. To that end, many prior art devices are compared of various configurations of metal or similar durable material which are embedded in the pavement surface by various methods; U.S. Pat. Nos. 1,606,825; 1,678,215; 2,127,233; and 1,728,275. U.S. Pat. No. 1,966,318 discloses a traffic marker composed of a thin ribbon of aluminum foil fastened to the pavement by adhesive means. This thin ribbon of foil is in reality little more than a rolled-up painted line glued to the pavement. As a result it suffers many of the same disadvantages as the painted line. While each of these devices does achieve some permanency, the savings achieved in avoiding the cost of repaintings has not been sufficient to offset the cost of manufacturing and, particularly, installing such permanent markers.
It is noted that the devices disclosed in U.S. Pat. Nos. 1,678,215; 1,728,275; and 2,127,233 show undersurface configurations which are relatively complex. Such devices would, because of that complexity, be expensive to manufacture and install. In addition, installation would be time-consuming, resulting in prolonged disruption of traffic, required maintenance of traffic detours, and increased labor costs. It is further noted that none of the prior devices are adapted for economical installation in existing pavement and particularly so with regard to new or existing asphaltic pavement.
In addition, such prior devices are particularly unsuited for use with asphaltic pavements because of the flexible character of such pavements. Asphaltic pavements tend to soften when heated by the sun and as a result are continually kneaded in all directions by passing vehicular traffic. Because of their rigid installation, the above prior art devices cannot adapt to this constant kneading action of the asphaltic surface and will, in time, become exposed in whole or in part so as to project above the surface thereby posing a safety hazard to both vehicular and pedestrian traffic. While the device described in U.S. Pat. No. 1,606,825 is claimed to be suited for use with asphaltic surfaces, it is of a different construction and teaches away from the present invention.